Chronic idiopathic thrombocytopenic purpura. Splenic pathologic features and their clinical correlation.

We studied 83 patients who had chronic idiopathic thrombocytopenic purpura refractory to steroid therapy and who underwent splenectomy. The positive rates of antiplatelet and antinuclear antibodies were 40% (30/75 patients tested) and 41% (25/61 patients tested), respectively. The morphologic characteristics of splenic pathologic findings included prominent secondary follicles and foamy macrophages, present in 23 (28%) and 56 (67%) of patients, respectively. Extramedullary hematopoiesis was noted in 50 (60%) of the patients. Eight patients (10%) presented with periarterial fibrosis, and three of them had systemic lupus erythematosus. The 23 patients (28%) with prominent secondary follicles were younger than the other patients, were preponderantly female, and had a higher rate of antiplatelet antibody production, and all had an initial response with a greater increase in platelets postoperatively. Eight patients (10%) had neither prominent secondary follicles nor foamy macrophages and lower splenic weights; their initial response compared with that of other patients was significantly poorer. The thrombocytopenia in these patients might have a different mechanism.